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<pre><span class="sourceLineNo">001</span>/*<a name="line.1"></a>
<span class="sourceLineNo">002</span> * Licensed to the Apache Software Foundation (ASF) under one or more<a name="line.2"></a>
<span class="sourceLineNo">003</span> * contributor license agreements.  See the NOTICE file distributed with<a name="line.3"></a>
<span class="sourceLineNo">004</span> * this work for additional information regarding copyright ownership.<a name="line.4"></a>
<span class="sourceLineNo">005</span> * The ASF licenses this file to You under the Apache License, Version 2.0<a name="line.5"></a>
<span class="sourceLineNo">006</span> * (the "License"); you may not use this file except in compliance with<a name="line.6"></a>
<span class="sourceLineNo">007</span> * the License.  You may obtain a copy of the License at<a name="line.7"></a>
<span class="sourceLineNo">008</span> *<a name="line.8"></a>
<span class="sourceLineNo">009</span> *      http://www.apache.org/licenses/LICENSE-2.0<a name="line.9"></a>
<span class="sourceLineNo">010</span> *<a name="line.10"></a>
<span class="sourceLineNo">011</span> * Unless required by applicable law or agreed to in writing, software<a name="line.11"></a>
<span class="sourceLineNo">012</span> * distributed under the License is distributed on an "AS IS" BASIS,<a name="line.12"></a>
<span class="sourceLineNo">013</span> * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.<a name="line.13"></a>
<span class="sourceLineNo">014</span> * See the License for the specific language governing permissions and<a name="line.14"></a>
<span class="sourceLineNo">015</span> * limitations under the License.<a name="line.15"></a>
<span class="sourceLineNo">016</span> */<a name="line.16"></a>
<span class="sourceLineNo">017</span>package org.apache.commons.io.output;<a name="line.17"></a>
<span class="sourceLineNo">018</span><a name="line.18"></a>
<span class="sourceLineNo">019</span>import java.io.IOException;<a name="line.19"></a>
<span class="sourceLineNo">020</span>import java.io.OutputStream;<a name="line.20"></a>
<span class="sourceLineNo">021</span><a name="line.21"></a>
<span class="sourceLineNo">022</span>import org.apache.commons.io.function.IOConsumer;<a name="line.22"></a>
<span class="sourceLineNo">023</span>import org.apache.commons.io.function.IOFunction;<a name="line.23"></a>
<span class="sourceLineNo">024</span><a name="line.24"></a>
<span class="sourceLineNo">025</span>/**<a name="line.25"></a>
<span class="sourceLineNo">026</span> * An output stream which triggers an event when a specified number of bytes of data have been written to it. The event<a name="line.26"></a>
<span class="sourceLineNo">027</span> * can be used, for example, to throw an exception if a maximum has been reached, or to switch the underlying stream<a name="line.27"></a>
<span class="sourceLineNo">028</span> * type when the threshold is exceeded.<a name="line.28"></a>
<span class="sourceLineNo">029</span> * &lt;p&gt;<a name="line.29"></a>
<span class="sourceLineNo">030</span> * This class overrides all {@code OutputStream} methods. However, these overrides ultimately call the corresponding<a name="line.30"></a>
<span class="sourceLineNo">031</span> * methods in the underlying output stream implementation.<a name="line.31"></a>
<span class="sourceLineNo">032</span> * &lt;/p&gt;<a name="line.32"></a>
<span class="sourceLineNo">033</span> * &lt;p&gt;<a name="line.33"></a>
<span class="sourceLineNo">034</span> * NOTE: This implementation may trigger the event &lt;em&gt;before&lt;/em&gt; the threshold is actually reached, since it triggers<a name="line.34"></a>
<span class="sourceLineNo">035</span> * when a pending write operation would cause the threshold to be exceeded.<a name="line.35"></a>
<span class="sourceLineNo">036</span> * &lt;/p&gt;<a name="line.36"></a>
<span class="sourceLineNo">037</span> */<a name="line.37"></a>
<span class="sourceLineNo">038</span>public class ThresholdingOutputStream extends OutputStream {<a name="line.38"></a>
<span class="sourceLineNo">039</span><a name="line.39"></a>
<span class="sourceLineNo">040</span>    /**<a name="line.40"></a>
<span class="sourceLineNo">041</span>     * Noop output stream getter function.<a name="line.41"></a>
<span class="sourceLineNo">042</span>     */<a name="line.42"></a>
<span class="sourceLineNo">043</span>    private static final IOFunction&lt;ThresholdingOutputStream, OutputStream&gt; NOOP_OS_GETTER = os -&gt; NullOutputStream.NULL_OUTPUT_STREAM;<a name="line.43"></a>
<span class="sourceLineNo">044</span><a name="line.44"></a>
<span class="sourceLineNo">045</span>    /**<a name="line.45"></a>
<span class="sourceLineNo">046</span>     * The threshold at which the event will be triggered.<a name="line.46"></a>
<span class="sourceLineNo">047</span>     */<a name="line.47"></a>
<span class="sourceLineNo">048</span>    private final int threshold;<a name="line.48"></a>
<span class="sourceLineNo">049</span><a name="line.49"></a>
<span class="sourceLineNo">050</span>    /**<a name="line.50"></a>
<span class="sourceLineNo">051</span>     * Accepts reaching the threshold.<a name="line.51"></a>
<span class="sourceLineNo">052</span>     */<a name="line.52"></a>
<span class="sourceLineNo">053</span>    private final IOConsumer&lt;ThresholdingOutputStream&gt; thresholdConsumer;<a name="line.53"></a>
<span class="sourceLineNo">054</span><a name="line.54"></a>
<span class="sourceLineNo">055</span>    /**<a name="line.55"></a>
<span class="sourceLineNo">056</span>     * Gets the output stream.<a name="line.56"></a>
<span class="sourceLineNo">057</span>     */<a name="line.57"></a>
<span class="sourceLineNo">058</span>    private final IOFunction&lt;ThresholdingOutputStream, OutputStream&gt; outputStreamGetter;<a name="line.58"></a>
<span class="sourceLineNo">059</span><a name="line.59"></a>
<span class="sourceLineNo">060</span>    /**<a name="line.60"></a>
<span class="sourceLineNo">061</span>     * The number of bytes written to the output stream.<a name="line.61"></a>
<span class="sourceLineNo">062</span>     */<a name="line.62"></a>
<span class="sourceLineNo">063</span>    private long written;<a name="line.63"></a>
<span class="sourceLineNo">064</span><a name="line.64"></a>
<span class="sourceLineNo">065</span>    /**<a name="line.65"></a>
<span class="sourceLineNo">066</span>     * Whether or not the configured threshold has been exceeded.<a name="line.66"></a>
<span class="sourceLineNo">067</span>     */<a name="line.67"></a>
<span class="sourceLineNo">068</span>    private boolean thresholdExceeded;<a name="line.68"></a>
<span class="sourceLineNo">069</span><a name="line.69"></a>
<span class="sourceLineNo">070</span>    /**<a name="line.70"></a>
<span class="sourceLineNo">071</span>     * Constructs an instance of this class which will trigger an event at the specified threshold.<a name="line.71"></a>
<span class="sourceLineNo">072</span>     *<a name="line.72"></a>
<span class="sourceLineNo">073</span>     * @param threshold The number of bytes at which to trigger an event.<a name="line.73"></a>
<span class="sourceLineNo">074</span>     */<a name="line.74"></a>
<span class="sourceLineNo">075</span>    public ThresholdingOutputStream(final int threshold) {<a name="line.75"></a>
<span class="sourceLineNo">076</span>        this(threshold, IOConsumer.noop(), NOOP_OS_GETTER);<a name="line.76"></a>
<span class="sourceLineNo">077</span>    }<a name="line.77"></a>
<span class="sourceLineNo">078</span><a name="line.78"></a>
<span class="sourceLineNo">079</span>    /**<a name="line.79"></a>
<span class="sourceLineNo">080</span>     * Constructs an instance of this class which will trigger an event at the specified threshold.<a name="line.80"></a>
<span class="sourceLineNo">081</span>     *<a name="line.81"></a>
<span class="sourceLineNo">082</span>     * @param threshold The number of bytes at which to trigger an event.<a name="line.82"></a>
<span class="sourceLineNo">083</span>     * @param thresholdConsumer Accepts reaching the threshold.<a name="line.83"></a>
<span class="sourceLineNo">084</span>     * @param outputStreamGetter Gets the output stream.<a name="line.84"></a>
<span class="sourceLineNo">085</span>     * @since 2.9.0<a name="line.85"></a>
<span class="sourceLineNo">086</span>     */<a name="line.86"></a>
<span class="sourceLineNo">087</span>    public ThresholdingOutputStream(final int threshold, final IOConsumer&lt;ThresholdingOutputStream&gt; thresholdConsumer,<a name="line.87"></a>
<span class="sourceLineNo">088</span>        final IOFunction&lt;ThresholdingOutputStream, OutputStream&gt; outputStreamGetter) {<a name="line.88"></a>
<span class="sourceLineNo">089</span>        this.threshold = threshold;<a name="line.89"></a>
<span class="sourceLineNo">090</span>        this.thresholdConsumer = thresholdConsumer == null ? IOConsumer.noop() : thresholdConsumer;<a name="line.90"></a>
<span class="sourceLineNo">091</span>        this.outputStreamGetter = outputStreamGetter == null ? NOOP_OS_GETTER : outputStreamGetter;<a name="line.91"></a>
<span class="sourceLineNo">092</span>    }<a name="line.92"></a>
<span class="sourceLineNo">093</span><a name="line.93"></a>
<span class="sourceLineNo">094</span>    /**<a name="line.94"></a>
<span class="sourceLineNo">095</span>     * Checks to see if writing the specified number of bytes would cause the configured threshold to be exceeded. If<a name="line.95"></a>
<span class="sourceLineNo">096</span>     * so, triggers an event to allow a concrete implementation to take action on this.<a name="line.96"></a>
<span class="sourceLineNo">097</span>     *<a name="line.97"></a>
<span class="sourceLineNo">098</span>     * @param count The number of bytes about to be written to the underlying output stream.<a name="line.98"></a>
<span class="sourceLineNo">099</span>     *<a name="line.99"></a>
<span class="sourceLineNo">100</span>     * @throws IOException if an error occurs.<a name="line.100"></a>
<span class="sourceLineNo">101</span>     */<a name="line.101"></a>
<span class="sourceLineNo">102</span>    protected void checkThreshold(final int count) throws IOException {<a name="line.102"></a>
<span class="sourceLineNo">103</span>        if (!thresholdExceeded &amp;&amp; written + count &gt; threshold) {<a name="line.103"></a>
<span class="sourceLineNo">104</span>            thresholdExceeded = true;<a name="line.104"></a>
<span class="sourceLineNo">105</span>            thresholdReached();<a name="line.105"></a>
<span class="sourceLineNo">106</span>        }<a name="line.106"></a>
<span class="sourceLineNo">107</span>    }<a name="line.107"></a>
<span class="sourceLineNo">108</span><a name="line.108"></a>
<span class="sourceLineNo">109</span>    /**<a name="line.109"></a>
<span class="sourceLineNo">110</span>     * Closes this output stream and releases any system resources associated with this stream.<a name="line.110"></a>
<span class="sourceLineNo">111</span>     *<a name="line.111"></a>
<span class="sourceLineNo">112</span>     * @throws IOException if an error occurs.<a name="line.112"></a>
<span class="sourceLineNo">113</span>     */<a name="line.113"></a>
<span class="sourceLineNo">114</span>    @Override<a name="line.114"></a>
<span class="sourceLineNo">115</span>    public void close() throws IOException {<a name="line.115"></a>
<span class="sourceLineNo">116</span>        try {<a name="line.116"></a>
<span class="sourceLineNo">117</span>            flush();<a name="line.117"></a>
<span class="sourceLineNo">118</span>        } catch (final IOException ignored) {<a name="line.118"></a>
<span class="sourceLineNo">119</span>            // ignore<a name="line.119"></a>
<span class="sourceLineNo">120</span>        }<a name="line.120"></a>
<span class="sourceLineNo">121</span>        getStream().close();<a name="line.121"></a>
<span class="sourceLineNo">122</span>    }<a name="line.122"></a>
<span class="sourceLineNo">123</span><a name="line.123"></a>
<span class="sourceLineNo">124</span>    /**<a name="line.124"></a>
<span class="sourceLineNo">125</span>     * Flushes this output stream and forces any buffered output bytes to be written out.<a name="line.125"></a>
<span class="sourceLineNo">126</span>     *<a name="line.126"></a>
<span class="sourceLineNo">127</span>     * @throws IOException if an error occurs.<a name="line.127"></a>
<span class="sourceLineNo">128</span>     */<a name="line.128"></a>
<span class="sourceLineNo">129</span>    @SuppressWarnings("resource") // the underlying stream is managed by a subclass.<a name="line.129"></a>
<span class="sourceLineNo">130</span>    @Override<a name="line.130"></a>
<span class="sourceLineNo">131</span>    public void flush() throws IOException {<a name="line.131"></a>
<span class="sourceLineNo">132</span>        getStream().flush();<a name="line.132"></a>
<span class="sourceLineNo">133</span>    }<a name="line.133"></a>
<span class="sourceLineNo">134</span><a name="line.134"></a>
<span class="sourceLineNo">135</span>    /**<a name="line.135"></a>
<span class="sourceLineNo">136</span>     * Returns the number of bytes that have been written to this output stream.<a name="line.136"></a>
<span class="sourceLineNo">137</span>     *<a name="line.137"></a>
<span class="sourceLineNo">138</span>     * @return The number of bytes written.<a name="line.138"></a>
<span class="sourceLineNo">139</span>     */<a name="line.139"></a>
<span class="sourceLineNo">140</span>    public long getByteCount() {<a name="line.140"></a>
<span class="sourceLineNo">141</span>        return written;<a name="line.141"></a>
<span class="sourceLineNo">142</span>    }<a name="line.142"></a>
<span class="sourceLineNo">143</span><a name="line.143"></a>
<span class="sourceLineNo">144</span>    /**<a name="line.144"></a>
<span class="sourceLineNo">145</span>     * Returns the underlying output stream, to which the corresponding {@code OutputStream} methods in this class will<a name="line.145"></a>
<span class="sourceLineNo">146</span>     * ultimately delegate.<a name="line.146"></a>
<span class="sourceLineNo">147</span>     *<a name="line.147"></a>
<span class="sourceLineNo">148</span>     * @return The underlying output stream.<a name="line.148"></a>
<span class="sourceLineNo">149</span>     *<a name="line.149"></a>
<span class="sourceLineNo">150</span>     * @throws IOException if an error occurs.<a name="line.150"></a>
<span class="sourceLineNo">151</span>     */<a name="line.151"></a>
<span class="sourceLineNo">152</span>    protected OutputStream getStream() throws IOException {<a name="line.152"></a>
<span class="sourceLineNo">153</span>        return outputStreamGetter.apply(this);<a name="line.153"></a>
<span class="sourceLineNo">154</span>    }<a name="line.154"></a>
<span class="sourceLineNo">155</span><a name="line.155"></a>
<span class="sourceLineNo">156</span>    /**<a name="line.156"></a>
<span class="sourceLineNo">157</span>     * Returns the threshold, in bytes, at which an event will be triggered.<a name="line.157"></a>
<span class="sourceLineNo">158</span>     *<a name="line.158"></a>
<span class="sourceLineNo">159</span>     * @return The threshold point, in bytes.<a name="line.159"></a>
<span class="sourceLineNo">160</span>     */<a name="line.160"></a>
<span class="sourceLineNo">161</span>    public int getThreshold() {<a name="line.161"></a>
<span class="sourceLineNo">162</span>        return threshold;<a name="line.162"></a>
<span class="sourceLineNo">163</span>    }<a name="line.163"></a>
<span class="sourceLineNo">164</span><a name="line.164"></a>
<span class="sourceLineNo">165</span>    /**<a name="line.165"></a>
<span class="sourceLineNo">166</span>     * Determines whether or not the configured threshold has been exceeded for this output stream.<a name="line.166"></a>
<span class="sourceLineNo">167</span>     *<a name="line.167"></a>
<span class="sourceLineNo">168</span>     * @return {@code true} if the threshold has been reached; {@code false} otherwise.<a name="line.168"></a>
<span class="sourceLineNo">169</span>     */<a name="line.169"></a>
<span class="sourceLineNo">170</span>    public boolean isThresholdExceeded() {<a name="line.170"></a>
<span class="sourceLineNo">171</span>        return written &gt; threshold;<a name="line.171"></a>
<span class="sourceLineNo">172</span>    }<a name="line.172"></a>
<span class="sourceLineNo">173</span><a name="line.173"></a>
<span class="sourceLineNo">174</span>    /**<a name="line.174"></a>
<span class="sourceLineNo">175</span>     * Resets the byteCount to zero. You can call this from {@link #thresholdReached()} if you want the event to be<a name="line.175"></a>
<span class="sourceLineNo">176</span>     * triggered again.<a name="line.176"></a>
<span class="sourceLineNo">177</span>     */<a name="line.177"></a>
<span class="sourceLineNo">178</span>    protected void resetByteCount() {<a name="line.178"></a>
<span class="sourceLineNo">179</span>        this.thresholdExceeded = false;<a name="line.179"></a>
<span class="sourceLineNo">180</span>        this.written = 0;<a name="line.180"></a>
<span class="sourceLineNo">181</span>    }<a name="line.181"></a>
<span class="sourceLineNo">182</span><a name="line.182"></a>
<span class="sourceLineNo">183</span>    /**<a name="line.183"></a>
<span class="sourceLineNo">184</span>     * Sets the byteCount to count. Useful for re-opening an output stream that has previously been written to.<a name="line.184"></a>
<span class="sourceLineNo">185</span>     *<a name="line.185"></a>
<span class="sourceLineNo">186</span>     * @param count The number of bytes that have already been written to the output stream<a name="line.186"></a>
<span class="sourceLineNo">187</span>     *<a name="line.187"></a>
<span class="sourceLineNo">188</span>     * @since 2.5<a name="line.188"></a>
<span class="sourceLineNo">189</span>     */<a name="line.189"></a>
<span class="sourceLineNo">190</span>    protected void setByteCount(final long count) {<a name="line.190"></a>
<span class="sourceLineNo">191</span>        this.written = count;<a name="line.191"></a>
<span class="sourceLineNo">192</span>    }<a name="line.192"></a>
<span class="sourceLineNo">193</span><a name="line.193"></a>
<span class="sourceLineNo">194</span>    /**<a name="line.194"></a>
<span class="sourceLineNo">195</span>     * Indicates that the configured threshold has been reached, and that a subclass should take whatever action<a name="line.195"></a>
<span class="sourceLineNo">196</span>     * necessary on this event. This may include changing the underlying output stream.<a name="line.196"></a>
<span class="sourceLineNo">197</span>     *<a name="line.197"></a>
<span class="sourceLineNo">198</span>     * @throws IOException if an error occurs.<a name="line.198"></a>
<span class="sourceLineNo">199</span>     */<a name="line.199"></a>
<span class="sourceLineNo">200</span>    protected void thresholdReached() throws IOException {<a name="line.200"></a>
<span class="sourceLineNo">201</span>        thresholdConsumer.accept(this);<a name="line.201"></a>
<span class="sourceLineNo">202</span>    }<a name="line.202"></a>
<span class="sourceLineNo">203</span><a name="line.203"></a>
<span class="sourceLineNo">204</span>    /**<a name="line.204"></a>
<span class="sourceLineNo">205</span>     * Writes {@code b.length} bytes from the specified byte array to this output stream.<a name="line.205"></a>
<span class="sourceLineNo">206</span>     *<a name="line.206"></a>
<span class="sourceLineNo">207</span>     * @param b The array of bytes to be written.<a name="line.207"></a>
<span class="sourceLineNo">208</span>     *<a name="line.208"></a>
<span class="sourceLineNo">209</span>     * @throws IOException if an error occurs.<a name="line.209"></a>
<span class="sourceLineNo">210</span>     */<a name="line.210"></a>
<span class="sourceLineNo">211</span>    @SuppressWarnings("resource") // the underlying stream is managed by a subclass.<a name="line.211"></a>
<span class="sourceLineNo">212</span>    @Override<a name="line.212"></a>
<span class="sourceLineNo">213</span>    public void write(final byte[] b) throws IOException {<a name="line.213"></a>
<span class="sourceLineNo">214</span>        checkThreshold(b.length);<a name="line.214"></a>
<span class="sourceLineNo">215</span>        getStream().write(b);<a name="line.215"></a>
<span class="sourceLineNo">216</span>        written += b.length;<a name="line.216"></a>
<span class="sourceLineNo">217</span>    }<a name="line.217"></a>
<span class="sourceLineNo">218</span><a name="line.218"></a>
<span class="sourceLineNo">219</span>    /**<a name="line.219"></a>
<span class="sourceLineNo">220</span>     * Writes {@code len} bytes from the specified byte array starting at offset {@code off} to this output stream.<a name="line.220"></a>
<span class="sourceLineNo">221</span>     *<a name="line.221"></a>
<span class="sourceLineNo">222</span>     * @param b The byte array from which the data will be written.<a name="line.222"></a>
<span class="sourceLineNo">223</span>     * @param off The start offset in the byte array.<a name="line.223"></a>
<span class="sourceLineNo">224</span>     * @param len The number of bytes to write.<a name="line.224"></a>
<span class="sourceLineNo">225</span>     *<a name="line.225"></a>
<span class="sourceLineNo">226</span>     * @throws IOException if an error occurs.<a name="line.226"></a>
<span class="sourceLineNo">227</span>     */<a name="line.227"></a>
<span class="sourceLineNo">228</span>    @SuppressWarnings("resource") // the underlying stream is managed by a subclass.<a name="line.228"></a>
<span class="sourceLineNo">229</span>    @Override<a name="line.229"></a>
<span class="sourceLineNo">230</span>    public void write(final byte[] b, final int off, final int len) throws IOException {<a name="line.230"></a>
<span class="sourceLineNo">231</span>        checkThreshold(len);<a name="line.231"></a>
<span class="sourceLineNo">232</span>        getStream().write(b, off, len);<a name="line.232"></a>
<span class="sourceLineNo">233</span>        written += len;<a name="line.233"></a>
<span class="sourceLineNo">234</span>    }<a name="line.234"></a>
<span class="sourceLineNo">235</span><a name="line.235"></a>
<span class="sourceLineNo">236</span>    /**<a name="line.236"></a>
<span class="sourceLineNo">237</span>     * Writes the specified byte to this output stream.<a name="line.237"></a>
<span class="sourceLineNo">238</span>     *<a name="line.238"></a>
<span class="sourceLineNo">239</span>     * @param b The byte to be written.<a name="line.239"></a>
<span class="sourceLineNo">240</span>     *<a name="line.240"></a>
<span class="sourceLineNo">241</span>     * @throws IOException if an error occurs.<a name="line.241"></a>
<span class="sourceLineNo">242</span>     */<a name="line.242"></a>
<span class="sourceLineNo">243</span>    @SuppressWarnings("resource") // the underlying stream is managed by a subclass.<a name="line.243"></a>
<span class="sourceLineNo">244</span>    @Override<a name="line.244"></a>
<span class="sourceLineNo">245</span>    public void write(final int b) throws IOException {<a name="line.245"></a>
<span class="sourceLineNo">246</span>        checkThreshold(1);<a name="line.246"></a>
<span class="sourceLineNo">247</span>        getStream().write(b);<a name="line.247"></a>
<span class="sourceLineNo">248</span>        written++;<a name="line.248"></a>
<span class="sourceLineNo">249</span>    }<a name="line.249"></a>
<span class="sourceLineNo">250</span>}<a name="line.250"></a>




























































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